As for example shown at FIG. 1A, a prior art motor vehicle has a high temperature, fast flow rate, cooling system 10 for cooling the internal combustion engine 20 via engine coolant heat exchange with the atmosphere at an engine heat exchanger (radiator) 12, and further has a moderate (low to middle-range) temperature, low flow rate, cooling system 14 for cooling of auxiliary vehicle components 22, as for example vehicle hybrid electronics, engine turbo/super chargers, etc., via auxiliary coolant heat exchange with the atmosphere at an auxiliary heat exchanger (radiator) 16.
It is conventional practice to include the engine heat exchanger 12 and a condenser 18 of the heating, ventilation, air conditioning (HVAC) system 26 of the motor vehicle into a condenser, radiator and fan module (CRFM) assembly 28, as for example described in U.S. Pat. No. 6,470,961, wherein, when present, the auxiliary heat exchanger 16 is also included in the CRFM assembly, as shown at FIG. 1A.
Motor vehicle applications of the moderate temperature cooling system 14 include, for example, hybrid motor vehicles and fuel cell motor vehicles. Hybrid motor vehicles utilize electrical components which supplement the internal combustion engine, as for example a power inverter and/or an electric drive motor, and other electrical components. Problematically, these electrical components generate heat which must be dissipated in order to operate within predetermined parameters. As such, a moderate temperature coolant system 14 is used to provide the heat dissipation, as needed. Fuel cell motor vehicles may also utilize a moderate temperature cooling system 14 for its electronic components, i.e., cooling of power inverters, electric drive motors, etc. Also, a moderate temperature cooling system 14 may be used with air-to-coolant charge air coolers, as for example either turbo-charged or supercharged powertrains. The high and moderate temperature cooling systems 10, 14 are entirely separate from each other in terms of components, coolant and functionality.
FIGS. 1B and 1C depict variations on the configuration of FIG. 1A, wherein like functioning parts have like numeral designations. In FIG. 1B, the high temperature cooling system 10′ is modified so that the fluid of the transmission 25 is cooled by incorporation with the engine heat exchanger 12′, as for example described in U.S. Pat. No. 5,186,245. In FIG. 1C, the configuration of FIG. 1B is modified further, in that the moderate temperature cooling system 14′ now has an anterior relocation of the auxiliary heat exchanger 16′.
Referring now additionally to FIG. 1D, additional details of the prior art high and moderate temperature cooling systems 10, 14 will be further discussed.
The high temperature cooling system 10 circulates an engine coolant 30, which is hot leaving the engine, through main coolant piping 32 to the engine heat exchanger (radiator) 12 where it is cooled, and then returns to the engine, wherein this circulation is provided by a water pump. The flow of engine coolant 30 is regulated by a thermostat, wherein the engine coolant typically has an operational temperature range of between 80 C and 127 C entering the engine heat exchanger and an operational temperature range of between 60 C and 120 C leaving the engine heat exchanger. No engine coolant flows in the event the thermostat is closed or when the internal combustion engine is turned off. The components of the high temperature coolant system 10 further include: an engine heat exchanger inlet tank 34 connected to engine heat exchanger passages 36 of the engine heat exchanger 12, an engine heat exchanger outlet tank 38 also connected to the engine heat exchanger passages, and an engine coolant reservoir 40 communicating with the engine heat exchanger outlet tank and having a pressure relief fill port 42.
The moderate temperature cooling system 14 includes auxiliary coolant piping 50, whereby an auxiliary coolant 52 flows through the auxiliary heat exchanger (radiator) 16 whereat heat of the coolant is exchanged with the atmosphere, and whereby heat is absorbed from various auxiliary vehicle components 22 which may be connected in series, parallel or series-parallel with respect to each other, and may include, for example traction power electronics, motors, accessory power supplies, alternators, engine turbo/super chargers, intercoolers, oil coolers (other than engine and transmission), etc. The auxiliary coolant 52 is fluidically connected to an auxiliary coolant reservoir (or surge tank) 58 which serves as a coolant flow-through in which a removable pressure relief cap 60 permits air escape and whereat auxiliary coolant filling is performed. A pump 62 powered by an electric motor is connected by the auxiliary coolant piping, wherein the inlet of the pump is connected to the auxiliary coolant reservoir 58 (which is, in turn, connected to an outlet side of the auxiliary heat exchanger 16), and the outlet of the pump is connected to the auxiliary vehicle components 22 (which are, in turn, connected to an inlet side of the auxiliary heat exchanger). The flow of auxiliary coolant typically has an operational temperature range of between 60° C. and 95° C. entering the auxiliary coolant heat exchanger and an operational temperature range of between 55° C. and 90° C. leaving the auxiliary coolant heat exchanger. The auxiliary coolant flows irrespective of flow of the engine coolant, as it is a separate system. The components of the moderate temperature coolant system 14 include: an auxiliary heat exchanger inlet tank 64 connected with auxiliary heat exchanger passages 66 of the auxiliary heat exchanger and an auxiliary heat exchanger outlet tank 68 also connected to the auxiliary heat exchanger passages.
With the addition of alternative power systems such as electric hybrid propulsion and the need for improved emissions and performance while simultaneously increasing fuel economy by adding enhancements such as forced engine induction, the moderate temperature cooling system 14 adds to the vehicle packaging, mass and cost burden. To be effective, the moderate temperature cooling system 14 requires auxiliary coolant temperatures that peak and average differently than that of engines and transmissions. Due to the amount of heat that is rejected by the typical engine, it is usually impractical to resize the engine thermal system to provide the temperature headroom required by the moderate temperature cooling system.
Accordingly, what remains needed in the art is an integrated high and moderate temperature cooling system for both the internal combustion engine and the auxiliary components of the motor vehicle that successfully addresses the aforementioned issues.